Biocontrol Potential of Talaromyces spp. Against Root-Knot Nematodes With Main Focus on T. pinophilus

Abstract

Root-knot nematodes (Meloidogyne spp.) pose a significant threat to global agriculture causing substantial yield losses. Talaromyces is a well-known biocontrol fungus used against the root-knot nematodes. To assess the diversity of nematophagous Talaromyces spp. from the rhizospheric soils, we employed a novel technique that used target root-knot nematode as prey to isolate the fungi. A total of 26 Talaromyces isolates belonging to 12 nominal species were identified across varied agroclimatic zones of India. Detailed morphological and molecular characterisation revealed the presence of T. adpressus, T. oumae-annae and T. veerkampii, hitherto unreported from India. Nine Talaromyces spp. found in the present investigation were not known to possess nematophagous ability to date. Nematophagous ability of the isolated fungal species was confirmed through in vitro studies using M. incognita and M. graminicola. The isolate F17 (T. pinophilus) was found to induce 100% mortality of the nematodes. Further, in vivo studies conducted with F17 isolate using M. incognita-tomato and M. graminicola-rice pathosystems showed up to 79.8% and 74.7% reduction in nematode galling, respectively, along with plant growth promotion. Expression of green fluorescent protein in the F17 isolate helped track the progress and nature of juvenile parasitism. The GC–MS profiling of volatile organic compounds in F17 revealed the presence of 32 bioactive components that reportedly contain nematicidal potential, thus corroborating the in vitro mortality. The performance of the fungal isolate F17 (T. pinophilus) inculcates high confidence to propose it as a prospective bioagent to be commercially developed for root-knot nematode management.